Plant roots release various organic materials that may modify soil structure and affect heat and mass transfer processes. The objective of this study was to determine the effects of a synthetic root exudate (SRE) on penetrometer resistance (PR), thermal conductivity (λ), hydraulic conductivity (k) and evaporation of water in a sandy soil. Soil samples, mixed with either distilled water or the SRE, were packed into columns at a designated bulk density and water content, and incubated for 7 days at 18oC. Soil PR, λ, k and evaporation rate were monitored during drying processes. Compared with those incubated with water, samples incubated with SRE had visible hyphae, greater PR (0.7-5.5 MPa higher) and λ (0.2-0.7 W m-1 K-1 higher) in the water content range of 0.11-0.22 and 0.05-0.22 m3 m-3, increased k in the wet region but decreased k in the dry region. SRE treatment also reduced the overall soil water evaporation rate and cumulative water loss. Analysis of CT scanning showed that the SRE treated samples had a greater proportion of small pores (< 60 m). These changes were attributed mainly to SRE-simulated microbial activities.

中文翻译：

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受合成根系分泌物培养影响的沙土物理特性：强度、导热性和水力传导性以及蒸发

植物根系释放各种有机物质，这些物质可能会改变土壤结构并影响传热和传质过程。本研究的目的是确定合成根系分泌物 (SRE) 对沙土中的渗透电阻 (PR)、热导率 (λ)、水力传导率 (k) 和水分蒸发的影响。与蒸馏水或 SRE 混合的土壤样品以指定的堆积密度和含水量装入柱中，并在 18oC 下培养 7 天。在干燥过程中监测土壤 PR、λ、k 和蒸发速率。与水培养的样品相比，SRE 培养的样品在 0.11-0.22 和 0.05 的含水量范围内具有明显的菌丝、更大的 PR（高 0.7-5.5 MPa）和 λ（高 0.2-0.7 W m-1 K-1） -0.22 m3 m-3, 潮湿地区的 k 增加，但干燥地区的 k 降低。SRE 处理还降低了整体土壤水分蒸发率和累积水分流失。CT 扫描分析表明，经 SRE 处理的样品具有较大比例的小孔（< 60 m）。这些变化主要归因于 SRE 模拟的微生物活动。